A third atomic bomb core never used on Japan killed two Los Alamos physicists in criticality accidents, then was melted down.

On February 2, 1851, a handful of Paris scientists received one of the strangest invitations in the history of science.

A glass teardrop that survives a hammer but explodes when you snap its tail puzzled the Royal Society for centuries. Here’s how frozen-in stress works, and where it hides in your car and phone.

A rolling bicycle with nobody on it can steer itself upright. For a century the credit went to gyroscopes and trail. Then a 2011 bike with neither proved the real story was stranger.

Solar Orbiter 2022, Norikura 1992, SDO 2012, SOHO’s whip, and the 1946 Grand Daddy — the best solar prominence images ever captured.

For decades, rocks on Death Valley’s Racetrack Playa left trails no one saw form. Then GPS-tagged stones and a lucky winter pond caught paper-thin ice pushing them along.

A tippe top turns itself upside down, a spun hard-boiled egg stands on end, and a rattleback refuses to spin the wrong way. Friction explains all three.

In 1943 Britain seriously planned a 2-million-ton aircraft carrier made of pykrete, frozen water mixed with wood pulp. Here’s how Project Habakkuk got from a bathtub to a Canadian lake, and why it never sailed.

The black box isn’t black. How a jazz fan’s wire recorder became aviation’s memory, why recorders are orange, and why some are never found.